<!DOCTYPE html>
<html class="reftest-wait">
  <body>
    <style>
      #a { border: 1px solid black; width: 100px; height: 100px; }
      #b { border: 1px solid blue; width: 50px; height: 50px; }
      div { position: absolute; }
    </style>
    <script>
      document.addEventListener("MozReftestInvalidate", function() {
        var a = document.querySelector("#a");
        var b = document.querySelector("#b");
        a.style.left = "10px";
        b.style.left = "20px";
        document.documentElement.removeAttribute("class");
      }, false);
    </script>
    <div id="a">
      <div id="b">
      </div>
    </div>
  </body>
</html>
